Process for knitting two-bar fabrics from three warp thread sets

ABSTRACT

This invention relates to a two-bar warp knitted fabric and method of forming the same with three warp thread sets in which two sets of threads are knitted or laid into the fabric with a normal tension to form a firm ground structure while a third set of threads is being knitted by one of the same bars while overfeeding the threads so that the loops of the actual stitch are forced out on the surface of the fabric.

United States Patent [1 Farmer et al.

PROCESS FOR KNITTING TWO-BAR FABRICS FROM THREE WARP THREAD SETS Inventors: Robert Clyde Farmer, Newark;

Harold Frederick Hume, Wilmington, both of Del.

E. I. du Pont de Nemours and Company, Wilmington, Del.

Filed: June 11, 1973 Appl. No.: 369,118

Assignee:

US. Cl 66/86 A Int. Cl D04b 23/00 Field of Search 66/86, 84, 190-195 References Cited UNITED STATES PATENTS Lesley 66/195 [451 Jan. 21, 1975 3,255,615 6/1966 Schwartz 66/194 FOREIGN PATENTS OR APPLICATIONS 2,070,334 10/1971 France 66/195 Primary ExaminerRonald Feldbaum This invention relates to a two-bar warp knitted fabric and method of forming the same with three warp thread sets in which two sets of threads are knitted or laid into the fabric with a normal tension to form a firm ground structure while a third set of threads is being knitted by one of the same bars while overt'eeding the threads so that the loops of the actual stitch are forced out on the surface of the fabric.

ABSTRACT 4 Claims, 2 Drawing Figures PATENTEBJANE 1 I975 SHEET 10F 2 FIG.

BACKGROUND OF THE INVENTION This invention relates to two-bar warp knitted fabrics and their manufacture.

Warp knitted fabrics made from continuous filament yarns are generally known to have a smooth and cold surface and handle.

It has been suggested before by various methods to let the yarn form small loops on the surface of the fabric by knitting or laying in one set of warp threads with very loose tension, that is, overfeeding one set of threads. Such fabrics are described in U.S. Pat. No. 3,254,510 and U.S. Pat. No. 3,277,673.

The weakness generally of such fabrics is a tendency to have a streaky and uneven surface and also that the small and loose loops are easily caught and pulled out of the fabric by sharp objects, or by wear giving a pilling effect. To overcome these difficulties, US. Pat. No. 3,517,530 teaches a process of producing a three-bar warp knit fabric by overfeeding the middle warp sheet to the middle bar. However, this requires a machine with three operating guide bars which generally operates at slower speed and increases the cost of fabric produced.

SUMMARY OF THE INVENTION In a process for producing warp knitted fabrics having loop formations on a warp knitting machine having at least three sets of warp threads of which at least two sets are fed with a normal thread feed rate to form a firm structure in the knitted fabric while at least one other set of warp threads is knitted into the fabric and is constantly overfed relative to feeding for normal stitch formation, the improvement comprising: knitting each of said other sets of threads in a different bar knitting threads with normal feed rate.

In the preferred embodiment, the warp knitting machine has three sets of warp threads of which two sets are fed with normal feed rate while the remaining or third set of warp threads is knitted into the fabric and is constantly overfed relative to feeding for normal stitch formation. The third set of threads is knitted by the same guides of one of the same bars knitting thread of normal feed rate. The overfeed set is fed to the needles without twisting or tangling and the amount of overfeed can be controlled from just above zero to over 100 percent.

Preferably, the knitted articles are formed from filament yarn. However, any other type of yarn acceptable to normal tricot knitting may be utilized.

BRIEF DESCRIPTION OF THE ILLUSTRATED EMBODIMENT FIG. 1 is a schematic drawing showing the relative positions of one needle position and two guide bars of a conventional bearded needle tricot knitting machine showing the additional yarn being overfed into the same guide alongside one of the conventional fed yarns.

FIG. 2 is a photograph of a fabric made with overfeed yarn as described in Example III.

vDETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT The invention may be practiced with a conventional warp knitting machine having two sets of yarn guides 11, 14, mounted on separate guide bars arranged for swing and lateral endwise movement with respect to a corresponding plurality of needles 15 mounted in a needle bar, not shown, which needles are movable up and down with respect to corresponding plurality of sinkers 17 which are moved in and out with respect to the needle 15 during the knitting cycle to effect the landing and knocking over of the loops. One set of yarns, illustrated by a single end 13 is threaded through a guide 14 of the back guide bar. Two sets of yarns, illustrated by single ends l0, 12 are threaded through another guide 11 of the front guide bar. The yarns are supplied to the guide bars from conventional warp beams, not shown, equipped to meter the desired amount of yarn by conventional gear drives on the warp beams.

In knitting of fabric in accordance with this invention, two warps of yarns l0 and 13 are fed at conventional rates, while one warp of yarn 12 is fed at a higher rate (overfed in comparison to yarn 10). As a result of the difference in feed rates, the overfed yarn provides a longer length of yarn in the stitch and underlap made by the needle. The effective stitch length of the stitches I8 is determined by the conventional fed yarns 10, I3 and the loop pile yarn in the stitches 18 formed from overfed yarn 12 accumulates in a larger loop portion of the stitches. This results in a portion of the stitches becoming raised from the surface of the fabric at the time of fabric formation. The needles may be of the bearded or latch type, the instant example being illustrated with respect to a bearded needle arrangement employing a conventional presser 16, which is movable in and out to selectively close and open the beards of the needles 15, as in the conventional knitting cycle of such machines. Any type of two-bar construction can be knit with this technique, such as, jersey, reverse jersey, long float, Delaware stitch, laid-in and partial threading effects such as simulated corduroy; Fabric produced by this invention can be finished by conventional finishing techniques and are particularly useful for making napped fabrics, sueded fabrics and surface effects such as terry and the like.

The adjustment of the knitting machine for proper clearances between moving parts is well understood by those skilled in the art of knitting. However, for preferred results, the recommended setting includes the following considerations: (1) tension bar for overfeed set should be rigid to help eliminate yarn flopping, (2) needles should be set approximately 0.5 mm. below sinker throat and (3) sinker throat should be approximately 2 mm. in front of needles.

The extent of the raised pile effect may be accentuated by adjustment of the difference in feed rate of the yarn sets supplied to the guide bars. This is evidenced by the following examples.

EXAMPLE I A 28-gauge Karl Mayer K-3 tricot knitting machine is equipped to carry three warp sets. One of the three guide bars is removed. Two warp sets are threaded in the guides of the front bar and one warp set is threaded in the guides of the back bar. The two warp sets threaded in the front bar contain 40 denier, 27 filament, dull, normal tenacity polyester yarn. The single warp set in the back bar contains 15 denier, semidull, normal tenacity monofilament nylon yarn. The maished by a conventional boil-off process and both the Greige and boil-off fabrics were analyzed. The results are tabulated in Table B.

chine is adjusted in a conventional manner to knit a 5 TABLE B l-/1-2 stitch on the front bar with both warp set 1 and 1 k h est a ric Control Fabric warp set yarns. The back bar 1s ad usted to kmt a (89% Named) (no marked) 2-3/1-0 stitch w1th the warp set 3 yarn. The feeding rates are adjusted to provide a 78 runner length for 3 5 7 9 warp set 1, a 45% inches runner length for warp set 2 10 jfi ji X 70 5' X X] and a 58 inch runner length for warp set 3 on the back ghlifikness (BSl) .044" .015"

u cc rn 9.40 3.83 bar. Fabrlc 1s knitted, scoured, napped, dyed and heat- Boiledofgf set. Weight. oz/yd* 4.] 3.7

In a similar manner, fabric is prepared for Fabrics 2, T F 3:15.1 3 4, 5, 6 and 7 according to the conditions summarized l5 Bulk cc/gm 7.21 3.64 in Table A TABLE A Front Bar Back Bar Fabric Quality" Beam Stitch Runner Stitch Runner Sets Pattern Length Overfeed*** Pattern Length Fabric 1 Set 1 1-0/1-2 *78" 71.5

Set 2 1-0/1-2 45%" Set 3 2 3/1-0 5s" 7" Fabric 2 Set I 1-0/2-3 55" Set 2 1-0/2-3 *75-se" 37 Set 3 0-1/1 0 36- /1" 6" Fabric 3 Set 1 1-0/1-2 42" Set 3 2-3/1-0 54" 7" Fabric 4 Set 1 1-0/2-3 67- Set 2 1-0/2-3 *99-W' 42 Set 3 1-2/1-0 41" 8" Fabric 5 Set 1 1-0/3-4 83" Set 2 1-0/3-4 *113- /1" 36.5

Set3 12/1-0 41-1&" 1;" Fabric 6 Set 1 l-0/3-4 72" Set 2 1-0/3-4 *101" 40 Set 3 0-1/1-0 e-vri" Fabric 7 Set I l-0/4-5 96-%" Set 2 1-0/4-5 *126" 30 Set 3 1 2/1-0 42 n" x-vt" Overfced Beam Set.

" Quality is defined as the inches in length ofGreige fabric produced in 480 courses. The measurement is made between the knitting elements and the fabric take-up rolls.

EXAMPLE ll A 28-gauge Mayer Tricot Machine is threaded with 70-34-T-l81 nylon (warp set 1 and 70-34-T-288 nylon (warp set 2) in the front guide bar, and -l3-T-28O nylon (warp set 3) in the back guide bar. The front bar is adjusted to knit a 2-3/1-0 stitch and back bar is adjusted to knit a l-O/l-2 stitch. The feed rates are adjusted to provide a 69 inch runner length for warp set 1 and a 125 inch runner length for warp set 2, giving an overfeed of 81 percent. The back bar (Warp set 3) is adjusted to provide a 54 inch runner length.

EXAMPLE III A 32-gauge Mayer Tricot Machine is threaded with 30-l0-T472 nylon in warp sets 1 and 2 in the front guide bar, and 15-1-T-280 nylon in the back guide bar. The front bar is adjusted to knit a 2-3/1-0 stitch, and back bar is adjusted to knit a 1-0/0-1 stitch. The feed rates are adjusted to provide a 54 inch runner for warp set 1 and 102 inch runner for warp set 2, giving an overfeed of 89 percent. The back bar is adjusted to provide a 52 inch runner for warp set 3. A 7 inch quality fabric is knit.

A control fabric is prepared using the same three warp sets and same machine settings. but without overfeeding warp set 2.

Bulk and thickness of the overfeed fabric is over 100 percent greater than the control. The fabrics were fin- It is possible to knit fabrics according to this invention with the overfeed warp in either the back bar or the front bar so long as the overfeed warp is threaded with one of the other warps of higher tension.

It is possible to utilize a variable path feeding device on the overfed thread set to control the thread during stitch formation. Such devices are commercially available for attachment to knitting machines. One such attachment is known as a .leseranda attachment.

Conventional finishing procedures are suitable for fabrics made according to this invention and the usual steps are scouring, dyeing and heat-setting. If desired, softening agents or other conventional processing agents can be applied.

What is claimed is:

1. In a process of producing warp knitted fabrics having loop formations on a warp knitting machine having three sets of warp threads of which two sets are fed with a normal thread feed rate to form a firm structure in the knitted fabric while a third set of warp threads is knitted into the fabric and is constantly overfed relative to feeding for normal stitch formation, each of said sets of threads being fed to operating guide bars of said knitting machine, the improvement comprising feeding one of said two sets to one of two operating guide bars of said knitting machine; feeding the other of said two sets to the other operating guide bar of said knitting machine; and knitting said third set of threads by the same gling with normally fed threads.

r 3,861,175 V 6 guides of one or the other operating guide bars of said 100 percent,

knitting machine. 4. The process as defined in claim 1, said overfed 2. The process aS defined m (5 fl Oveffed threads being fed to the guides through a varying path threads being fed to the guides without twisting or tanl h b a varying tension d i to Control l k 5 threads at the time of guide bar lateral movement. 3. The process as defined in claim 1, the amount of overfeed being controlled from just above zero to over 

1. In a process of producing warp knitted fabrics having loop formations on a warp knitting machine having three sets of warp threads of which two sets are fed with a normal thread feed rate to form a firm structure in the knitted fabric while a third set of warp threads is knitted into the fabric and is constantly overfed relative to feeding for normal stitch formation, each of said sets of threads being fed to operating guide bars of said knitting machine, the improvement comprising feeding one of said two sets to one of two operating guide bars of said knitting machine; feeding the other of said two sets to the other operating guide bar of said knitting machine; and knitting said third set of threads by the same guides of one or the other operating guide bars of said knitting machine.
 2. The process as defined in claim 1, said overfed threads being fed to the guides without twisting or tangling with normally fed threads.
 3. The process as defined in claim 1, the amount of overfeed being controlled from just above zero to over 100 percent.
 4. The process as defined in claim 1, said overfed threads being fed to the guides through a varying path length by a varying tension device to control slack threads at the time of guide bar lateral movement. 